Journal: Science Advances

Article Title: Tubulin polymerization dynamics are influenced by magnetic isotope effects consistent with the radical pair mechanism

doi: 10.1126/sciadv.ady8317

Figure Lengend Snippet: ( A ) Schematic representation of the magnetic field setup using Helmholtz coils. Tubulin samples containing Nat Mg(79% 24 Mg, 10% 25 Mg, 11% 26 Mg), 25 Mg, and 26 Mg were placed at the center of the Helmholtz coils, which generated a uniform magnetic field of 2.99 ± 0.02 mT (field on). ( B ) Box plots showing the median line, upper and lower quartile box, maximum and minimum whiskers, and scatter of individual replicates for the final OD measure of tubulin polymerization for Nat Mg, 25 Mg, and 26 Mg in the absence (blue) and presence (magenta) of the applied magnetic field of 2.99 ± 0.02 mT. OD values are in arbitrary units relative to the final values of tubulin polymerization with 26 Mg in the absence of an applied magnetic field. *** P < 10 −7 , difference from 25 Mg in the absence of an applied field as determined by a two-way ANOVA with a Tukey-Kramer post hoc test. Notably, neither Nat Mg nor 26 Mg show a significant difference between field-on and field-off conditions.

Article Snippet: Tubulin polymerization assay kits with >99% pure porcine tubulin were purchased from Cytoskeleton Inc. (BK006P).

Techniques: Generated

Journal: Science Advances

Article Title: Tubulin polymerization dynamics are influenced by magnetic isotope effects consistent with the radical pair mechanism

doi: 10.1126/sciadv.ady8317

Figure Lengend Snippet: ( A ) Comparison between the experimental data and radical F-pair model for microtubule density using 25 Mg (magenta), 26 Mg (blue), and 26 Mg (purple) under two conditions with exposure of 3 mT and the GMF of 0.05 mT. Experimental data are presented as means ± SD. Dashed lines connect model-predicted points at 0 and 3 mT for visualization only and do not indicate intermediate model values. The optimization procedure yielded a diverse set of parameter values that effectively capture the observed behavior across multiple conditions as indicated by the various dashed plots. The optimized values for the recombination rates were found to range from k rA = 1.1 × 10 5 to 1.4 × 10 5 s − 1 and k rB = 1.7 × 10 5 to 4.9 × 10 5 s − 1 . The singlet and triplet reaction rates varied between k S = 8.3 × 10 7 and 9.2 × 10 7 s − 1 and k T = 6.6 × 10 5 to 8 × 10 5 s − 1 , respectively. The HFCCs were optimized as a A = 0.01 mT, a 25 from 5.3 to 6.3 mT, and a B from 1.4 to 2.6 mT. This range of parameters are used in (B) and (C) as well. ( B ) Microtubule polymerization will be further reduced with 25 Mg at magnetic field strengths above 5 mT, compared to the levels observed at 3 mT. ( C ) Normalized microtubule density decreased under HMF conditions (<5 μT). In the classical microtubule model, the polymerization rate is k p = 5 × 10 − 5 s − 1 , the depolymerization rate is k d = 3 × 10 − 3 s − 1 , and the initial tubulin concentration is 3 g/liter.

Article Snippet: Tubulin polymerization assay kits with >99% pure porcine tubulin were purchased from Cytoskeleton Inc. (BK006P).

Techniques: Comparison, Concentration Assay

Journal: Science Advances

Article Title: Tubulin polymerization dynamics are influenced by magnetic isotope effects consistent with the radical pair mechanism

doi: 10.1126/sciadv.ady8317

Figure Lengend Snippet: ( A ) GTP (blue) hydrolyzes in the presence of a Mg 2+ ion (orange sphere) to produce GDP. ( B ) Crystal structure of α-tubulin (light gray) and β-tubulin (dark gray) with GTP (blue) and GDP (violet) in the nonhydrolyzable and hydrolyzable sites. ( C ) αβ-tubulin containing GTP (blue tubulin) at the hydrolyzable site polymerizes by attaching to the growing end of a microtubule to form the left-handed, helical, chiral microtubule structure with a hollow center. As the microtubule grows, tubulin hydrolyzes GTP with the aid of a Mg ion, causing the tubulin protein to flex. If the GTP cap on the end of the growing microtubule disappears, the flexed tubulin causes protofilaments to curve and separate from the microtubule, causing the microtubule to depolymerize in catastrophe. If additional GTP tubulin is added, the microtubule is rescued and continues to grow. Modified image from under a Creative Commons Attribution License.

Article Snippet: Tubulin polymerization assay kits with >99% pure porcine tubulin were purchased from Cytoskeleton Inc. (BK006P).

Techniques: Modification